The present invention relates in general to railway vehicle brake rigging slack adjuster assemblies and, more particularly, the invention relates to a triggering mechanism that activates the overtravel control apparatus of the slack adjuster in response to a measured travel distance of a fluid-pressure-operated brake cylinder piston rod.
For a number of years, slack adjusters have been provided as part of the brake rigging of railway vehicles to automatically compensate for the slack present in such brake rigging. This slack adjustment of the brake rigging is important for a variety of reasons. At least one significant reason is that with proper brake rigging movement, the brake cylinder piston rod travel distance can be maintained within a preselected travel distance.
In order for the slack adjuster assembly to adjust the slack in the brake rigging, an overtravel control mechanism is provided which is triggered in response to a measured and preset travel distance of the brake cylinder piston rod. In many installations, and particularly where the brake rigging is mounted on the trucks, the trigger placement becomes significantly more critical because of the limited space available to mount such trigger. Nevertheless, the number of such railway cars having truckmounted brake rigging is increasing because the slack adjuster assembly can be used as a force-transmitting member, thereby replacing one of the brake cylinders previously required.
Use of a slack adjuster assembly in this manner, therefore, offers the advantages of lower cost and reduced vehicle weight. On the other hand, this use requires that such slack adjuster assemblies have greater reliability. Further adding to the importance of maintaining a properly balanced brake rigging slack, is the fact that in normal practice, today's trains are made up with a greater number of cars which has been made possible because of increased power in the locomotive equipment.